1. Lesson Aims:
1. To understand how the river basin
hydrological cycle works.
2. To understand the factors that effect
the amount of water in the river
2. Water Flows
• Impermeable – water can’t permeate
through it (e.g. tramac, etc.)
• Permeable – water can permeate
through it (e.g. soil)
5. How does all this water get into the
rivers?
• On the mini white board draw a drainage
basin with a main river and tributary.
• Then add ‘real rain’ and show how it
moves down the rivers.
• What will make the ‘rain’ flow faster
into the main rivers?
8. Hydrographs
• These are graphs
that show the
amount of rainfall
and the volume of
water discharged
during a storm by a
river.
• Label your diagram
9. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
10. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
mm
4
3
2
Rainfall shown
in mm, as a
bar graph
11. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
mm
4
3
2
Discharge in
m3/s, as a
line graph
12. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
mm
4
3
2
The rising
flood water in
the river
13. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
mm
4
3
2
Peak flow
Peak flow
Maximum
discharge in
the river
14. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
mm
4
3
2
Peak flow
Falling flood
water in the
river
15. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
Basin lag time
mm
4
3
2
Peak flow
Basin lag time
Time
difference
between the
peak of the
rain storm
and the peak
flow of the
river
16. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
Base flow
Basin lag time
mm
4
3
2
Peak flow
Base flow
Normal
discharge of
the river
17. 0 12 24 36 48 30 72
Hours from start of rain storm
3
2
1
Discharge(m3/s)
Base flow
Through flow
Overland
flow
Basin lag time
mm
4
3
2
Peak flow
Overland flow
Through flow
+
=
Storm Flow